Purpose of the Case Study    Existing Infrastructure Associated With the Site    Local Transportation Infrastructure Assessment    Conclusions and Recommendations From the Assessment

Purpose and Scope of Assessment

Assessment of Local Bridge Condition (Ramp Street Bridge)

Visual Assessment of Pavement Condition (Mifflin Road)

Assessment of Pavement Strength (Mifflin Road)

Private Property Acquisition Issues and Turning Radii for Trucks

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In order to gain a better understanding of the process and infrastructure issues associated with the redevelopment of the Hays site, two methods of investigation were used in this case study. Since the Hays site is currently undergoing redevelopment, it was critical to interact with parties involved in the process and document the process, interactions, and information concerning transportation infrastructure issues.

In addition, a local infrastructure assessment of the site was performed. The purpose of the local infrastructure assessment was to "quantify" the condition of the existing transportation infrastructure in light of the changes that will be necessary for the redevelopment of the site as discussed in the previous section. The local infrastructure assessment included: condition assessment of an existing bridge structure (Ramp Street); condition assessment and design related to the pavement surface on Mifflin Road; and discussion of the current plans for increasing turning radii for the trucks on the local streets. Each of the three components of the local infrastructure assessment will be discussed in detail in the following sections.

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The following section involves a condition assessment of a local bridge near the Hays site (Ramp Street Bridge). This bridge was inspected in November of 1994 by Parsons Brinkerhoff Quade and Douglas, Inc. for the Allegheny County Department of Engineering and Construction. The information in this section concerning the bridge structure and condition was compiled from the Bridge Inspection Report (Parsons Brinkerhoff, 1994).

The Ramp Street Bridge, located within 25 feet of Ramp Street intersections with both Mifflin Road and Baldwin Road, spans over Street's Run (See Figure D-1, Appendix D), and is identified as Street's Run Bridge Number 2 (Allegheny County Bridge SZ02-0508).

The bridge structure, which was built in 1981, is a single span prestressed concrete adjacent box beam structure with a reinforced concrete deck, that carries two lanes of Ramp Street on an approximately 87 skew over Street's Run. The clear span of the structure is 36'-7", and the roadway width is 28'-0". Some of the features of this structure include: reinforced concrete parapets, reinforced concrete sidewalk (5-feet wide), standard aluminum pipe railing to the outside of the right barrier, beams supported by reinforced concrete abutments, and a six inch diameter gas line attached to the right fascia beam. This structure is not load posted and there are no vertical clearance restrictions. (Parsons Brinkerhoff, 1994)

There has been no major rehabilitation of the bridge structure since it was built in 1981. Before the inspection of this bridge in 1994, the last cursory inspection was conducted in 1992 by Neilan Engineers. (Parsons Brinkerhoff, 1994) Drawings for the bridge are included in Appendix D (See Figure D-2, Appendix D). The latest traffic data for the bridge was obtained in 1994; the average daily traffic at that time was 682 vehicles. (Parsons Brinkerhoff, 1994).

As mentioned previously, the inspection of this structure was performed by Parsons Brinkerhoff on November 4, 1994, in accordance with NBIS guidelines. A total of six major elements of the bridge structure were examined during the inspection process. The following is a summary of the condition of the major elements as determined through the inspection.

The first major element of the structure inspected were the approaches. Through the inspection procedure it was determined that: "the bituminous approach roadways were in generally fair condition; the near right corner approach settled slightly in the vicinity of the roadway drainage inlet; approximately five square feet of patches existed on the far approach slab; and the boxing glove type guardrail termination at the far left approach exhibited some minor collision damage." (Parsons Brinkerhoff, 1994) Also, it was found that "both approach slabs have heaved over time, causing the roadway and sidewalk surfaces, as well as the tops of the barriers, to be positioned from nearly 2 inches to as much as 2 3/8 inches above the adjacent bridge deck surfaces" and that "the inlets at the near left and right and far right approach quadrants were open and operating properly, however, due to the fact that the deck is at a lower elevation than the approaches, the deck has a tendency to pond water." (Parsons Brinkerhoff, 1994)

The second major element of the structure inspected was the bridge deck. It was determined through the inspection that: "the integral concrete wearing surface was in generally fair condition, with some longitudinal hairline cracks, a small spall at the near right corner measuring approximately one square foot in area and some small popouts." (Parsons Brinkerhoff, 1994) Also, it was noted that bituminous ramps at each end of the structure were placed in order to transition to the raised approach pavement. (Parsons Brinkerhoff, 1994)

The third major element of the structure inspected was the bridge superstructure. It was determined through the inspection that: "the prestressed concrete adjacent box beams were in good condition." (Parsons Brinkerhoff, 1994) Due to the fact that the neoprene bearing pads that support the beams were not visible, inspection of their condition was not possible.

The fourth major element of the structure inspected was the bridge substructure. It was determined through the inspection that: "both abutment stems exhibited one full-height hairline crack on the right half (facing abutments); no appreciable scour had occurred, but debris and sediment had built up along the full length of both abutments; the reinforced concrete wingwalls (that transition to older retaining walls on the near and far left and near right corners) were in good condition; and measurements and observations made at the interface of the bridge and adjacent walls indicated that there had been no detectable settlement of the structure." (Parsons Brinkerhoff, 1994) Due to the fact that the footings were not visible, inspection of their condition was not possible.

The fifth major element of the structure inspected was the stream channel under the bridge. It was determined through the inspection that: "the channel alignment was good, with flow centered under the span; minor scour existed along the upstream right side of the waterway with an average depth of 6 inches; the stream bed material is sandy gravel with cobbles; and all retaining walls that line the stream channel were stable and embankment erosion was not posing any problems in the vicinity of the bridge structure." (Parsons Brinkerhoff, 1994)

The sixth major element of the structure inspected were safety features of the bridge. It was determined through the inspection that: "the reinforced concrete barriers on the bridge met current standards and were in good condition; the guide-rail, which is only present at the far left approach, was not gradually stiffened as it approaches the bridge and its boxing glove end was damaged; and the barrier transitions at the other three corners consisted of sloping, tapering barriers, although not a desired condition, it is generally acceptable in congested areas where it is impractical to place approach guide-rail due to the presence of driveways, sideways and related roadway features." (Parsons Brinkerhoff, 1994)

The structure was analyzed to assess its live load capacity. This analysis was performed using the "Prestressed Concrete Girder" computer program (Commonwealth of Pennsylvania Department of Transportation). It was determined that the operating ratings for the structure were above minimums for the loadings specified and that the structure did not require posting of load limits, however, both the HS25 and ML80 inventory ratings were below desired levels. (Parsons Brinkerhoff, 1994) The following table contains a summary of the results from the structural analysis of the bridge structure.

Table 5.1: Summary of Results From Structural Analysis of Ramp Street Bridge (Parsons Brinkerhoff, 1994)

The following is a discussion of the conclusions and recommendations from the Bridge Inspection Report (Parsons Brinkerhoff, 1994). Concerning the load limits, it was concluded that no load limitations were required at that time. Concerning immediate repairs or improvements, repair and upgrading of the box glove end treatment at the far end of the far left approach guide-rail was recommended. Concerning required repairs or improvements, in addition to recommending the repair of the sidewalks, it was recommended that the deck be overlayed and effectively sealed in order to remove the ramp effect and allow the deck to drain properly. It was suggested that the misalignment of the approach parapets, roadway, and sidewalk surfaces be monitored and be repaired, should the condition worsen. The estimated cost for immediate repairs was $1000 and for required repairs $7450. The estimated remaining service life of the structure was 30 years, provided that the recommended repairs were undertaken and a service life of 15 years, should the repairs not be undertaken. (Parsons Brinkerhoff, 1994).

The following discussion of the current condition of the Ramp Street Bridge is based on recommendations by Wilbur Smith Consults, the engineering firm contracted to design for the current transportation infrastructure improvements at the Hays site, and visual inspection of the structure by the author (See Figures B-10 through B13, Appendix B).

It was concluded by Wilbur Smith Consultants that the Ramp Street bridge structure was structurally capable and acceptable to handle the new traffic associated with the redevelopment of the Hays site. This conclusion was based on the bridge inspection information in the Parsons Brinkerhoff report as discussed in the previous sections. However, some improvements will be made to the surface of the bridge structure as related to improvements for increasing turning radii for the trucks on the local streets. These improvements, which including the Ramp Street Bridge improvements will be discussed in later sections.

Through visual inspection of the Ramp street bridge, the major deficiencies as described in the Parsons Brinkerhoff Report, appear to be present. However, the severity of the deficiencies has not increased significantly since the last inspection of the bridge in 1994. This conclusion was reached based on visual assessment of the structure by the author. It should be noted that many of the major deficiencies with the structure will be corrected through the improvements that will be made for increasing turning radii for the trucks on Ramp Street. The Ramp Street Bridge is due to be inspected by the Allegheny County Department of Engineering and Construction in 1997, as part of its bridge inspection program (according to NBIS guidelines).

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There are many possible approaches to defining performance and assessing the condition of road facilities. The purpose of this procedure is to determine, through visual condition assessment, the condition of the pavement on a street located near the Hays site. The assessment was accomplished by using PAVER, a method developed by the Army Corps of Engineers. (Shahin, 1981)

The PAVER condition assessment procedure is based on visual assessment of the type, quantity and severity of pavement distresses and results in the pavement condition index (PCI). The assessment area is located on Mifflin Road near the Hays plant as shown in Figure 5.2 below (Also, See Figure E-1, Appendix E and Figures B-14 through B-16, Appendix B). The method used and the results of the assessment procedure will be discussed in detail in the following sections.

Figure 5.1: PAVER Assessment Area (Mifflin Road) Near Hays Site (Source: Modified From D&L Inc., 1996)

A visual condition assessment of the pavement of a street located near the Hays site was performed using a method developed by the Army Corps of Engineers. As mentioned above, the area examined in this exercise located on Mifflin Road (See Figure E-1, Appendix E). The following is a description of the procedure used to assess the condition of the pavement.

The first step in the procedure involved the identification of a representative area within the parking lot. Following the recommendation of Shahin of 2500 + 1000 square feet, a rectangular area of 20 feet by 187 feet (3740 square feet) was chosen and the corners of the area were marked (Shahin, 1981). The sample area was chosen due to its location near the ramp intersection. This area is of interest because truck traffic will be traveling both to and from the Hays site via this section of Mifflin Road.

The second step in the procedure involved the identification both type and severity of the pavement distresses present in the study area of the road section. This procedure was performed with the use of the U.S. Army Corps "Pavement Condition Index (PCI) Field Manual" which contains definitions and information concerning pavement distresses. Each of the various types of pavement distresses were identified and measured (i.e. units of linear feet or square feet, etc.). In addition, for each distress, a level of severity was determined [low (L), Medium (M), High (H)]. The data for the distresses were recorded on Form B "Asphalt Pavement Inspection Sheet" (See Figure E-2, Appendix E).

Once the visual assessment of the representative area of the road was complete, calculations were performed using the data collected in the field. Through these calculations, a pavement condition index (PCI) for the parking lot was determined. The following section will discuss the calculations in more detail.

Using the data obtained through the assessment procedure (See Figure E-2, Appendix E), the following calculations were performed to determine the pavement condition index (PCI) for the sample area. All of the information obtained through the following calculations was recorded on Form B (See Figure E-2, Appendix E).

First, for each of the different types of distresses, a distress density was calculated. The following are the formulas (Equations 5.1 through 5.3) that were used to calculate the distress densities:

Figure 5.1: Equations 5.1 through 5.3 (Source: Shahin, 1981)

The values for the densities were recorded on Form B (See Figure E-2, Appendix E). Next, using the calculated densities and the severity (i.e. L, M, or H) a deduct value for each distress type was determined. The deduct values were determined through the use of the "Deduct Value Curves" for each of the various distress types identified. The curves are part of the U.S. Army Corps of Engineers Technical Report M-294 (See Figures E-3 through E-9, Appendix E). The deduct values for all the distresses were then summed to produce a "Deduct Total." Given the "Deduct Total" and a value for the number of deducts greater than 5 points (q), Figure E-10 (See Appendix E) was used to determine a "Corrected Deduct Value" or (CDV). Finally, the pavement condition index (PCI) was calculated using the following equation:

PCI = 100 - CDV (Equation 5.4)

Given the value of the PCI for the road section, a pavement condition rating was determined using Figure E-11 (See Appendix E).

The original raw data that was collected in the field and the results of the calculation described in the previous section are included on Form B (See Figure E-2, Appendix E). The following table is a summary of the data and results:

Table 5.2: Summary of Results for PAVER Assessment of Mifflin Road Section

As shown in Table 5.1, there were seven different types of distresses identified during the inspection of the representative area on Mifflin Road. The levels of severity for the seven distresses identified ranged from low severity (L) to high severity (H). The total amount of "Deduct" was found to be 239 and the corrected deduct value (CDV) was determined to be 78. The pavement condition index (PCI) was determined to be 22 which results in a rating of "Very Poor" for the road section based on the rating index provided (See Figure E-11, Appendix E).

There are several possible sources of error in this exercise which may have effected the rating which was determined. A major source of error in the results is the experience of the inspector that performed the evaluation. Since this was only the second time the inspector performed this type of pavement assessment, a lack of experience may have affected the results. Although this inspection was performed with the use of the U.S. Army Corps "Pavement Condition Index (PCI) Field Manual" which contains definitions and information concerning pavement distresses, identification of the various distresses is a difficult process without any prior experience to base judgments on. Thus, the inspector may have been "over-aggressive" in determining the distresses present which resulted in the low rating that was obtained. In addition, all of the measurements for extent of each distress measured (i.e. units of linear feet or square feet, etc.) were performed without the use of a measuring device. The measurements were approximated using crude methods (i.e. pacing) and subjective judgment. Thus, poor approximations of the extent of the various distresses present may have resulted in the low rating obtained. Also, there were several sources of error in the method used to perform the calculations for the PCI. As described in previous sections, the deduct values were determined through the use of the "Deduct Value Curves" for each of the various distress types identified. Thus, errors in reading the values from the curves could have affected the results. Furthermore, given that the "Deduct Total" and the value for the number of deducts greater than 5 points (q) were both off the scale of Figure E-10 (See Appendix E) which was used to determine a "Corrected Deduct Value" or (CDV), some error is associated with reading the value from the curve. This could have effected the resulting PCI rating.

In addition to the sources of error in the procedure as discussed above, there are several other factors which may have affected the results. One consideration is the process of selection used to determine the location for the assessment area. As mentioned previously, a rectangular area of 20 feet by 187 feet (3740 square feet) was chosen. This area was chosen to represent the worse case scenario of pavement condition for Mifflin Road. Selection of a different sample area on Mifflin road might have resulted in a higher PCI rating.

Overall, the procedure used in this exercise seemed to be a fairly good method for assessment of pavement condition if performed properly. However, lack of experience on the part of the inspector and the use of imprecise measurement methods may have resulted in the "Very Poor" rating that was obtained for the road section. This point illustrates a key limitation of the procedure. Due to the importance of the inspector's judgment in the process and the effects it can have on the PCI, it is imperative that inspectors performing the evaluation be properly trained. Although properly trained and experienced inspectors can perform more accurate assessments through this method, variances among different inspectors will always exist and may produce ratings that are not consistent or truly uniform in all respects.

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In addition to the visual condition assessment of the pavement surface of Mifflin Road, an assessment of the strength of the pavement was performed. As in the case of visual assessment of pavement condition, there are many possible approaches to assess the strength of asphalt pavement structures used in road facilities. The purpose of this procedure is to determine, through pavement thickness design evaluation, the ability of the pavement on a street located near the Hays site to support heavy truck traffic that will be using this road to access the Hays site once the plant is in operation. The assessment was accomplished by using a method developed by The Asphalt Institute.

This procedure which involves pavement thickness design, uses factors for traffic (i.e. position, volume, type, etc.), pavement structure characteristics (i.e. condition, type, and thickness of subgrade and courses), and results in an over-all thickness of the asphalt pavement structure necessary to meet the requirements specified. The assessment area is located on Mifflin Road near the Hays plant as shown in Figure 5.2 (Also, See Figure C-5, Appendix C). The method used and the results of the assessment procedure will be discussed in detail in the following sections.

An assessment of the strength of the pavement structure for a street located near the Hays site was performed using a method developed by The Asphalt Institute. As mentioned above, the area examined in this exercise located on Mifflin Road (See Figure C-5, Appendix C). The following is a description of the procedure used to assess the strength of the pavement structure.

The first step in the procedure involved the determination of a Design Traffic Number (DTN) for Mifflin Road. Again, Mifflin Road is of interest because truck traffic will be traveling both to and from the Hays site via artery. In order to determine the DTN for Mifflin Road, it was necessary to estimate the Initial Daily Traffic (IDT) volume which includes all types of vehicles. The average daily traffic volume for ramp street, which leads to Mifflin Road, was determined to be 682 vehicles in 1994 (Parsons Brinkerhoff, 1994). An estimated total of 50 trucks will be shipping steel to and from the hays site once the plant is in operation and a total of 75 new jobs are to be created at the hays plant. (Marc Knezevich, URA, 1996) Adding these numbers to the average daily traffic volume results in an estimated Initial Daily Traffic (IDT) volume of 807 vehicles.

Given the Initial Daily Traffic (IDT) volume and using a classification of "Secondary Rural Road", Figure F-1 (See Appendix F) was used to determine the Design Traffic Number (DTN) for Mifflin Road. Figure F-1 is based on a design period of 20 years and on an anticipated, uniform growth of traffic amounting to 80 percent of the initial daily traffic during the design period. (The Asphalt Institute, 1963) The classification of "Secondary Rural Road", was chosen due to its definition which states: "traffic usually is comprised of about 85 percent or more of automobiles and trucks...the upper portion of the zone for this class of traffic should be used where the volume of heavily-loaded trucks is expected to be relatively large...roads serving industrial, logging, or mining operations should fall into this category." (The Asphalt Institute, 1963) The Initial Daily Traffic (IDT) volume for Mifflin Road, calculated by using Figure F-1 (See Appendix F), was determined to have a value of 30.

The second step in the procedure involved evaluation of the subsurface conditions of Mifflin Road. Normally, mechanical strength tests are performed on subgrade soils, in the laboratory or in situ, and these tests are supplemented by classification tests. (The Asphalt Institute, 1963) "Mechanical strength tests are performed to evaluate each of the different soils encountered on a given site. The classification tests permit the identification of different soils during construction and help identify undesirable soils such as those susceptible to frost heave." (The Asphalt Institute, 1963)

Since test data was not available and it was impractical to perform such tests within the scope of this assessment, approximate correlation with AASHO and Unified Soil Classification Systems given in Figure F-2 (See Appendix F) were used, as recommended in the Asphalt Institute procedure. (The Asphalt Institute, 1963) Based on specifications and plans for Mifflin Road (Wilbur Smith Consultants, 1996) it was assumed that the subsurface conditions of Mifflin Road are acceptable. Using the upper limit of the "Acceptable" range for sub-base in Figure F-2, an equivalent California Bearing Ratio (CBR) of 30 was obtained for Mifflin Road subsurface materials.

The third step of the procedure involved the determination of the total design thickness of the asphalt surfacing (TA) for Mifflin Road. This value was determined using Figure F-3 (See Appendix F) using values of 30 and 30 for the parameters DTN and CBR determined in the previous steps. The resulting value for the total design thickness of the asphalt surfacing (TA) for Mifflin Road, determined from Figure F-3 was 4.5 inches.

The following table is a summary of the data and results of the thickness assessment procedure as described in the previous section.

Table 5.3: Summary of Results of Pavement Thickness Assessment (Mifflin Road)

As shown in Table 5.3 the total design thickness of the asphalt surfacing (TA) for Mifflin Road, obtained from The Asphalt Institute procedure was determined to be 4.5 inches. Based on specifications and plans for Mifflin Road (Wilbur Smith Consultants, 1996) as shown in the cross section detail in Figure F-4 (See Appendix F), this value appears to be acceptable. The results suggest that the pavement structure of Mifflin Road is capable of supporting heavy truck traffic that will be using this road to access the Hays site once the plant is in operation.

Due to the fact that the design procedure used in this assessment process involves many assumptions, it is possible that sources of error may have effected the results. A major source of error in the procedure involved the evaluation of the subsurface conditions. Due to the fact that test data was not available and it was impractical to perform such tests within the scope of the assessment, the use of approximate correlation produce a source of error in the results. Also, although the procedure developed by The Asphalt Institute appears to be well formulated, many other design procedure could be used to determine the design thickness of the pavement structure, which may have produced different results.

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The following section involves discussion of plans for improvements in turning radii for the trucks on the local streets near the hays site. This work will be part of transportation infrastructure improvements near the Hays site assessed and designed by Wilbur Smith Consultants, the engineering firm contracted by PEIDC. The information in this section improvements in turning radii for the trucks on the local streets near the hays site was compiled from the GalvTech Site North and South Access Design documents and plans (Wilbur Smith Consultants, 1996).

This project which involves both the north and south entrances near the Hays site includes: construction of new roadway pavement, curbs, drainage piping and structures, grading, driveway adjustment, sign-age, and street lighting. More specifically the work includes: "approximately 1,500 square yards of concrete roadway pavement, 4,075 square yards of bituminous pavement, 850 linear feet of concrete curb, roadway drainage, street lighting, pavement marking work, and all work incidental thereto." (Wilbur Smith Consultants, 1996). The following sections describe in detail the work related to each of the entrances (north and south) involved in this project.

The location plan for the GalvTech North Access project is shown in Figure G-1, Appendix G. (Also, See Figures B-17 through B-20, Appendix B) As shown in Figure G-1, the work for the North Entrance component of the project involves Old Eighth Avenue, Mifflin Road, and Baldwin Street. Major tasks include: the construction of new entrance, North Access (including construction of new storm drainage inlets and piping and concrete curbs), on property previously owned by the SandCastle Recreational Park; milling of existing pavement surface and resurfacing with new Bituminous pavement a major portion of Baldwin Street approaching the SandCastle entrance; and the installation of new street lighting. A detailed plan for the North Access project is shown in Figure G-2.

It should be noted that the purpose of the majority of the work for the North Entrance component of the project is to provide improvements in turning radii for the trucks that will be delivering the steel to the plant once it becomes operational.

The location plan for the GalvTech South Access project is shown in Figure G-3, Appendix G. (Also, See Figures B-10 through B-13, Appendix B) As shown in Figure G-3, the work for the South Entrance component of the project involves primarily Ramp Street and its intersections with Mifflin Road and Baldwin Street. Major tasks include: the construction of new concrete pavement along the entire length of Ramp Street (including construction of new storm drainage inlets and piping, concrete curbs, and approach slabs for the bridge); widening of the roadway intersection with Mifflin Road; and widening of the roadway intersection with Baldwin Street. A detailed plan for the South Access project is shown in Figure G-4.

It should be noted that the purpose of the majority of the work for the South Entrance component of the project is to provide improvements in turning radii for the trucks that will be delivering the steel to the plant once it becomes operational.

Web Pages for the Hays Site Created By: J.P. Barton,Carnegie Mellon University.
Questions or Comments: Send E-mail to: dlange@cmu.edu
Last Updated: August 20, 1999